Shutter disk and blade alignment sensor

ABSTRACT

The present invention generally provides a physical vapor deposition chamber and a method for detecting a position of a shutter disk within a physical vapor deposition chamber. In one embodiment, a physical vapor deposition chamber includes a chamber body having a shutter disk mechanism disposed therein. A housing is sealingly coupled to a sidewall of the chamber body and communicates therewith through a slot formed through the sidewall. At least a first sensor is disposed adjacent to the housing and orientated to detect the presence of a shutter disk mechanism within the housing. In one embodiment, a method for detecting the position of a shutter disk within a physical vapor deposition chamber having a substrate support generally includes moving the shutter disk away from a substrate support, and changing a state of a first sensor in response to a position of an edge the shutter disk.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] Embodiments of the invention generally relate to a physical vapordeposition chamber.

[0003] 2. Description of the Related Art

[0004] Many semiconductor processes are typically performed in a vacuumenvironment. For example, physical vapor deposition (PVD) is generallyperformed in a sealed chamber having a pedestal for supporting thesubstrate disposed thereon. The pedestal typically includes a substratesupport that has electrodes disposed therein to electrostatically holdthe substrate against the substrate support during processing. A targetgenerally comprised of a material to be deposited on the substrate issupported above the substrate, typically fastened to a top of thechamber. A plasma formed from a gas, such as argon, is supplied betweenthe substrate and the target. The target is biased, causing ions withinthe plasma to be accelerated toward the target. Ions impacting thetarget cause material to become dislodged from the target. The dislodgedmaterial is attracted toward a substrate and deposits a film of materialthereon.

[0005] Generally, two conditioning operations are performed in the PVDchamber to ensure process performance. A first conditioning process isknown as burning-in the target. Target burn-in generally removes oxidesand other contaminants from the surface of the target and is typicallyperformed after the chamber has been exposed to atmosphere or idled fora period of time. During the burn-in process, a utility wafer or shutterdisk is disposed on the substrate support to prevent deposition oftarget material on the support. The burn-in process generally comprisesforming a plasma within the chamber and using that plasma to remove thesurface layer of material from the target.

[0006] A second conditioning process is known as pasting. Pastinggenerally applies a covering over material deposited on chambercomponents during a conventional PVD process. For example, PVDapplication of titanium nitride generally results in a layer of titaniumnitride on the PVD chamber surfaces. The titanium nitride layer istypically brittle and may flake off during subsequent processes. Pastinggenerally applies a layer of titanium over the titanium nitride layer.The titanium layer substantially prevents the underlying titaniumnitride from flaking or peeling. Typically, the chamber is pasted atpredetermined intervals, such as after every 25 substrates are processedusing a conventional titanium nitride PVD process. As with targetburn-in, a shutter disk is disposed on the substrate support to preventdeposition of target material thereon during the pasting process.

[0007] Additionally, in PVD processes where titanium and titaniumnitride are sequentially applied in-situ, the target requires cleaningprior to each titanium deposition to remove nitrides that be present onthe target from titanium nitride deposited on the prior substrate.Generally, target cleaning is similar to a burn-in process having a fewsecond duration and includes protecting the substrate support with ashutter disk.

[0008] After completion of each burn-in, pasting and cleaning process,the shutter disk is rotated by a robotic arm disposed within the PVDchamber to a cleared position where the shutter disk does not interferewith the deposition process within the chamber. To center the positionof the shutter disk, a sensor is employed on a shaft coupled to therobotic arm to detect the rotational position of the arm.

[0009] A problem with this arrangement for detecting the position of theshutter disk in the cleared position is that the sensor does not havethe capability of confirming the relative position of the shutter diskto the robotic arm. For example, misalignment between the shutter diskand the robotic arm may result in a portion of the shutter diskremaining in the path of the ceramic substrate support. As the ceramicsupport is elevated into a process position, a portion of the substratemay contact the shutter disk, which may result in damage to thesubstrate or misalignment of the substrate on the ceramic support.Moreover, if the shutter disk comes in contact with the ceramic support,the ceramic support may become chipped or damaged and necessitatereplacement. Additionally, if the shutter disk is not properly alignedon the robotic arm, the disk may be misaligned relative to the ceramicsupport during the burn-in and pasting process, thereby resulting inunwanted deposition on a portion of the ceramic support. Depositionmaterial on the ceramic support may lead to particular generation,scratching of the wafer and a deterioration of process performance.

[0010] Therefore, there is a need for a PVD processing chamber having animproved shutter disk sensing system.

SUMMARY OF THE INVENTION

[0011] A physical vapor deposition chamber and a method for detecting aposition of a shutter disk within a physical vapor deposition chamberare generally provided. In one embodiment, a physical vapor depositionchamber includes a chamber body having a shutter disk mechanism disposedtherein. A housing is sealingly coupled to a sidewall of the chamberbody and communicates therewith through a slot formed through thesidewall. At least a first sensor is disposed adjacent to the housingand is orientated to detect the presence of a shutter disk mechanismwithin the housing.

[0012] In another embodiment, a physical vapor deposition processingchamber includes a chamber body that has a shutter blade and a substratesupport disposed therein. The shutter blade is adapted to support ashutter disk and is rotatable between a first position at leastpartially disposed in the housing and a second position within thechamber body proximate the substrate support. A housing is sealinglycoupled to a sidewall of the chamber body and communicates therewiththrough a slot formed through the sidewall. A first sensor is disposedproximate the housing and is orientated to detect the presence of theshutter disk viewed by the first sensor through a first window formed inthe housing when the blade is in the first position.

[0013] In another aspect of the invention, a method for detecting theposition of a shutter disk within a physical vapor deposition chamberhaving a substrate support is provided. In one embodiment, a method fordetecting the position of a shutter disk within a physical vapordeposition chamber having a substrate support includes moving theshutter disk from a first position substantially concentric with thesubstrate support to a second position clear of the substrate support,and sensing the edge of the shutter disk in the clear position.

[0014] In another embodiment, a method for detecting the position of ashutter disk within a physical vapor deposition chamber having asubstrate support includes moving the shutter disk away from thesubstrate support, and changing the state of a first sensor in responseto a position of an edge the shutter disk.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more particular description of the invention, brieflysummarized above, may be had by reference to the embodiments thereof,which is illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only typical embodimentsof this invention and are therefore not to be considered limiting of itsscope, for the invention may admit to other equally effectiveembodiments.

[0016]FIG. 1 depicts a semiconductor processing chamber having oneembodiment of a sensor assembly adapted to detect a position of ashutter disk mechanism;

[0017] FIGS. 2A-B are sectional and plan views of a portion of theprocess chamber of FIG. 1; and

[0018]FIG. 3 depicts a sectional view of the sensor assembly taken alongsection line 3-3 of FIG. 4.

[0019] To facilitate understanding, identical reference numerals havingbeen used, wherever possible, to designate identical elements that arecommon to the figures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0020] The invention generally provides a semiconductor processingsystem having a sensor assembly adapted to detect a cleared position ofa utility wafer, such as a shutter disk. The cleared position is definedas a position where a substrate support (and substrate seated thereon)may move vertically without contacting the shutter disk or mechanismsassociated with the movement of the shutter disk. Although the inventionis described in a physical vapor deposition chamber, the disclosure isone of illustration, and accordingly, the invention finds utility inother semiconductor processing chambers where it is advantageous toconfirm a cleared position of a utility wafer or other device which maybe disposed over a substrate support between substrate processingoperations.

[0021]FIG. 1 depicts a semiconductor process chamber 100 that includesone embodiment of a sensor assembly 110 adapted to detect a clearedposition of a utility wafer or shutter disk 114. Generally, the sensorassembly 110 is utilized to ensure that the shutter disk 114 is not in aposition that would contact a substrate support 104 or a substrate 112seated thereon during processing. One example of a process chamber 100that may be adapted to benefit from the invention is an IMP VECTRA™ PVDprocess chamber, available from Applied Materials, Inc., located inSanta Clara, Calif.

[0022] The exemplary process chamber 100 includes a chamber body 102 andlid assembly 106 that define an evacuable process volume 160. Thechamber body 102 is typically fabricated from a unitary block ofaluminum or welded stainless steel plates. The chamber body 102generally includes sidewalls 152 and a bottom 154. The sidewallsgenerally contain a plurality of apertures that include an access port,pumping port and a shutter disk port 156 (access and pumping ports notshown). The sealable access port provides for entrance and egress of thesubstrate 112 from the process chamber 100. The pumping port is coupledto a pumping system (also not shown) that evacuates and controls thepressure within the process volume 160. The shutter disk port 156 isconfigured to allow at least a portion of the shutter disk 114therethrough when the shutter disk 114 is in the cleared position. Ahousing 116 generally covers the shutter disk port 156 to maintain theintegrity of the vacuum within the process volume 160.

[0023] The lid assembly 156 of the body 100 generally supports anannular shield 162 suspended therefrom that supports a shadow ring 158.The shadow ring 158 is generally configured to confine deposition to aportion of the substrate 112 exposed through the center of the shadowring 158.

[0024] The lid assembly 156 generally includes a target 164 and amagnetron 166. The target 164 provides material that is deposited on thesubstrate 112 during the PVD process while the magnetron 166 enhancesuniform consumption of the target material during processing. The target164 and substrate support 104 are biased relative each other by a powersource 184. A gas such as argon is supplied to the process volume 160from a gas source 182. A plasma is formed between the substrate 112 andthe target 164 from the gas. Ions within the plasma are acceleratedtoward the target 164 and cause material to become dislodged from thetarget 164. The dislodged target material is attracted towards thesubstrate 112 and deposits a film of material thereon.

[0025] The substrate support 104 is generally disposed on the bottom 154of the chamber body 102 and supports the substrate 112 duringprocessing. The substrate support 104 is coupled to the bottom 154 by alift mechanism (not shown) that is configured to move the substratesupport 104 between a lower (as shown) and an upper position. Thesubstrate support 104 is moved into the upper position for processing.In the upper position, the substrate 112 is disposed on the substratesupport 104 and engages the shadow ring 158, lifting the shadow ring 158from the shield 162.

[0026] In the lower position, the substrate support 104 is positionedbelow the shield 162 that allows the substrate 112 to be removed fromthe chamber 100 through the port in the sidewall 152 while clearing thering 158 and shield 162. Lift pins (not shown) are selectively movedthrough the substrate support 104 to space the substrate 112 from thesubstrate support 104 to facilitate securing of the substrate 112 by awafer transfer mechanism disposed exterior to the process chamber 100such as a single blade robot (not shown). A bellows 186 is typicallydisposed between the substrate support 104 and the chamber bottom 154and provides a flexible seal therebetween, thereby maintaining vacuumintegrity of the chamber volume 160.

[0027] The substrate support 104 is typically fabricated from aluminum,stainless steel, ceramic or combinations thereof. One substrate support104 that may be adapted to benefit from the invention is described inU.S. Pat. No. 5,507,499, issued Apr. 16, 1996 to Davenport et al., whichis incorporated herein by reference in its entirety.

[0028] A shutter disk mechanism 108 is generally disposed proximate thesubstrate support 104. The shutter disk mechanism 108 generally includesa blade 118 that supports the shutter disk 114 and an actuator 126coupled to the blade 118 by a shaft 120. A rotary seal 122 is disposedthrough the chamber bottom 154 to allow rotation of the shaft 120without vacuum leakage from the process volume 160.

[0029] The actuator 126 generally controls the angular orientation ofthe blade 118. Typically, the blade 118 is moved between the clearedposition shown in FIG. 1 and a second position that places the shutterdisk 114 substantially concentric with the substrate support 104. In thesecond position, the shutter disk 114 may be transferred (by utilizingthe lift pins) to the substrate support 104 during the target burn-inand chamber pasting process. Typically, the blade 118 is returned to thecleared position during the target burn-in and chamber pasting process.

[0030] The actuator 126 may be any device that may be adapted to rotatethe shaft 120 through an angle that moves the blade 118 between thecleared and second positions. The actuator 126 may be an electric,hydraulic or air motor, a pneumatic or hydraulic cylinder, or a solenoidamong other motion devices. The actuator 126 may include a shaft sensor124 that detects when the shaft 120 is rotated to the second position.The shaft sensor 124 may be directly coupled to the actuator 126, aswith a rotary encoder or limit switch, or may interface with the shaft120, as with a limit switch. Other sensors 124 that may be adapted todetect the angular position of the shaft 120 may also be utilized.

[0031] The blade 118 generally supports the shutter disk 114 in ahorizontal orientation. The blade 118 typically has a flat body thatincludes a hub 128 that is coupled to the shaft 120, and at least threedisk support pins 130 extending therefrom. The pins 130 generallysupport the shutter disk 114 in a spaced-apart relation to the blade118. The blade 118 is configured to allow rotation of the blade 118 fromthe second position to the cleared position without contacting the liftpins extending from the blade 118. The blade 118 additionally includes atab 220 (shown in FIG. 2A) that extends beyond the perimeter of theshutter disk 114.

[0032] A portion of the shutter disk 114 is disposed in the housing 116when in the cleared position. The housing 116 is typically fabricatedfrom the same material as the chamber body 102. The housing 116 issealingly fastened to the chamber body 102, and in one embodiment, iscontinuously welded at the interface between the housing 116 and body102 to ensure a vacuum-tight joint.

[0033] The housing 116 generally includes at least a first window 134sealingly disposed through the housing 116. The first window 134 ispositioned to allow the sensor assembly 110 to detect the presence ofthe shutter disk 114 and/or the blade 118 within the housing 116. In theembodiment depicted in FIG. 1, the housing 116 additionally includes asecond window 136 formed in a bottom section 140 of the housing 116opposite the first window 134 that is formed in a top section 138 of thehousing 116. The windows 134, 136 are fabricated from a materialsubstantially transparent or non-invasive to the detection mechanism ofthe sensor assembly 110, for example, quartz.

[0034] The sensor assembly 110 is generally disposed proximate thehousing 116. The sensor assembly 110 generally includes at least onesensor that is adapted to detect the presence of the blade 118 and/orshutter disk 114 within the housing 116, preferably when in the clearedposition.

[0035] The sensor assembly 110 is coupled to a controller 190 thatinterfaces with and typically controls the processing system 100. Thecontroller 190 typically comprises a central processing unit (CPU) 194,support circuits 196 and memory 192. The CPU 194 may be one of any formof computer processor that can be used in an industrial setting forcontrolling various chambers and sub-processors. The memory 192 iscoupled to the CPU 194. The memory 192, or computer-readable medium, maybe one or more of readily available memory such as random access memory(RAM), read only memory (ROM), floppy disk, hard disk, or any other formof digital storage, local or remote. The support circuits 196 arecoupled to the CPU 194 for supporting the processor in a conventionalmanner. These circuits include cache, power supplies, clock circuits,input/output circuitry, subsystems, and the like. The sensors, at leastincluding one of the sensor assembly 110 and the shaft sensor 124,provide information to the controller 190 regarding the position of theshutter disk 114 and/or the blade 118.

[0036] FIGS. 2A-B depict top and sectional plan views of the housing 116illustrating one embodiment of the sensor assembly's position relativeto the shutter disk 114, the blade 118 and the substrate support 104.The reader is encouraged to refer to both 2A-2B simultaneously.

[0037] In the embodiment depicted in FIGS. 2A-B, the sensor assemblyincludes a first sensor 202, a second sensor 204 and a third sensor 206.The sensors 202, 204 and 206 are respectfully coupled to the top 134 ofthe housing 116 by brackets 208, 210 and 212. The sensors 202, 204 and206 generally provide a signal indicative of the presence of the shutterdisk 114 and/or blade 118 thereunder.

[0038] The first and second sensors 202, 204 typically are positioned ona line 224 defined between a center point 214 of the substrate support104 and reference point 216. The reference point 216 is generallylocated at the center of the shutter disk 114 when the shutter disk 114is in the clear position (as shown). In one embodiment, the center andreference points 214, 216 are also equidistant from a central axis 218of the shaft 120. The position of the sensors 202, 204 along the line224 allows the sensors to provide a reliable indication that the shutterdisk 114 is clear of the substrate support 104 as the line 224 liesalong the shortest distance between the shutter disk 114 (whenpositioned correctly on the blade 118) and the substrate support 104.

[0039] The first sensor 202 generally detects the position of theshutter disk 114 when in the cleared position. The second sensorgenerally detects the shutter disk 222 when the disk is mis-positionedon the blade 118 but still detected by the first sensor 202 as shown byphantom shutter disk 222. For example, the shutter disk 222 may bepositioned off-centered on the blade 118, which places the disk 222further into the housing 116. Although the off-center position of theshutter disk 222 will still enable the substrate support to be movedvertically without contacting the shutter disk 222, the shutter disk 222will be misaligned with the substrate support 104 when rotated to thesecond position for pasting or target burn-in, which will allow materialto be disadvantageously deposited on the substrate support 104. Thus,the second sensor 204 indicates shutter disk 114 misalignment to thecontroller 190 which signals the operator or stops the productionsequence is an appropiate point for service. [0001]

[0040] The third sensor 206 is generally positioned to view a portion ortab 220 of the blade 118 to indicate that the blade 118 is in thecleared position. The tab 220 of the blade 118 may be covered by theshutter disk 114 or extend beyond the shutter disk 114 to allowdetection of the blade 118 when the disk 114 is also in the clearedposition. Alternatively, the third sensor 206 may be positioned to viewthe substrate through the second window 134 or other window disposed inthe housing 116.

[0041]FIG. 3 depicts a sectional view of one embodiment of the sensors202, 204 taken along section line 3-3 in FIG. 2A. The sensors 202, 204generally include an emitter 302 and a receiver 304. The emitter 302generates a signal, such as a light beam 306, that passes through thewindows 134, 136 and impinges upon the receiver 304. When the shutterdisk 114 blocks or interrupts the beam 306, the sensors 202, 204 changestate to indicate the presence of the shutter disk 114. Examples ofsensors 202, 204 that may be utilized to detect the shutter disk 114 areavailable Banner Engineering Corporation, located in Minneapolis, Minn.Other types of sensors, including reflective sensors (i.e., a devicehaving the emitter and receiver configured into a single unit) mayalternatively be utilized. The third sensor 206 is similarly configuredto detect the presence of the blade 118.

[0042] While the foregoing is directed to the preferred embodiment ofthe present invention, other and further embodiments of the inventionmay be devised without departing from the basic scope thereof, and thescope thereof is determined by the claims that follow.

What is claimed is:
 1. A physical vapor deposition chamber comprising: achamber body having sidewalls and a bottom defining a process volume; ashutter disk mechanism at least partially disposed in the processvolume; a slot formed through the sidewall; a housing sealingly coupledto the chamber body; and at least a first sensor disposed adjacent tothe housing and orientated to detect the presence of a portion of theshutter disk mechanism within the housing.
 2. The processing chamber ofclaim 1, wherein the housing further comprises a window formed therein,the first sensor viewing the shutter mechanism through the window. 3.The chamber of claim 2, wherein the window is quartz.
 4. The chamber ofclaim 1 further comprising a second sensor disposed adjacent to thehousing and orientated to detect the presence within the housing of theshutter mechanism.
 5. The chamber of claim 1, wherein the shuttermechanism further comprises: a rotatable shaft; a blade coupledperpendicularly to the shaft; and a shutter disk removably disposed onthe blade.
 6. The chamber of claim 5, further comprising a second sensordisposed adjacent to the first sensor, the first and second sensorsorientated to detect the presence within the housing of at least one ofthe blade and the shutter disk.
 7. The chamber of claim 6, furthercomprising a third sensor disposed adjacent to the first and secondsensors, the third sensor orientated to detect the presence of the bladewithin the housing.
 8. The processing chamber of claim 1, wherein thehousing further comprises: a first window formed through a first portionof the housing: and a second window formed through a second portion ofthe housing, the first sensor viewing the shutter mechanism whenpositioned between the windows.
 9. The chamber of claim 8, wherein thefirst sensor further comprises: an emitter disposed proximate the firstwindow; and a receiver disposed proximate the second window and linearlyaligned with the emitter, first window and second window.
 10. A physicalvapor deposition processing chamber comprising: a chamber body havingsidewalls and a bottom; a substrate support disposed in the chamberbody; a slot formed in the sidewalls; a housing sealingly coupled to thechamber body and around the perimeter of the slot; at least a firstwindow disposed in the housing; a shutter blade adapted to support ashutter disk, the shutter blade rotatable between a first position atleast partially disposed in the housing and a second position within thechamber body proximate the substrate support; and a first sensordisposed proximate the housing and orientated to detect the presence ofthe shutter disk viewed through the first window when the blade is inthe first position.
 11. The chamber of claim 10, further comprising: asecond sensor disposed proximate the housing and orientated to detectthe presence of the shutter disk viewed through the first window whenthe shutter blade is in the first position.
 12. The chamber of claim 11,wherein the second sensor is disposed radially outward the first sensorrelative to the substrate support.
 13. The chamber of claim 11, furthercomprising: a third sensor disposed proximate the housing and orientatedto detect the presence of the shutter blade viewed through the firstwindow when the blade is in the first position.
 14. The chamber of claim11 further comprising: a shaft sealingly disposed through the chamberbottom and coupled to the shutter blade; and a shaft sensor disposedexterior to the chamber and orientated to detect the presence of theshutter blade in the second position by a rotational orientation of theshaft.
 15. The chamber of claim 12, wherein the first sensor, the secondsensor and the substrate support are linearly aligned.
 16. A physicalvapor deposition processing chamber comprising: a chamber body havingsidewalls and a bottom; a substrate support disposed in the chamberbody; a slot formed in the sidewalls; a housing sealingly coupled to thechamber body and around the perimeter of the slot; at least a firstwindow disposed in the housing; a shutter disk disposed in the chamberbody, the shutter disk rotatable between a first position at leastpartially disposed in the housing and a second position within thechamber body proximate the substrate support; a first sensor disposedproximate the housing and orientated to detect the presence of theshutter disk viewed through the first window when the blade is in thefirst position; and a second sensor disposed radially outward the firstsensor relative to the substrate support, and orientated to detect thepresence of the shutter disk viewed through the first window.
 17. Amethod for detecting the position of a shutter disk within a physicalvapor deposition chamber having a substrate support, comprising: movingthe shutter disk from a first position substantially concentric with thesubstrate support to a second position clear of the substrate support;and sensing the edge of the shutter disk in the clear position.
 18. Themethod of claim 17, wherein the step of sensing the edge of the shutterdisk in the clear position further comprises: viewing the shutter diskthrough a window formed in a housing coupled to the chamber.
 19. Themethod of claim 17, wherein the step of sensing the edge of the shutterdisk in the clear position further comprises: interrupting a beamgenerated by an emitter and passing through a window formed in a housingcoupled to the chamber.
 20. The method of claim 17, wherein the step ofsensing the edge of the shutter disk in the clear position furthercomprises: sensing the edge of the shutter disk at a first radialdistance from the shutter disk; and sensing the edge of the shutter diskat a second radial distance from the shutter disk.
 21. The method ofclaim 20, wherein the step of sensing the edge of the shutter disk atthe first radial distance from the shutter disk occurs before the stepof sensing the edge of the shutter disk at the second radial distancefrom the shutter disk.
 22. The method of claim 20, wherein the step ofsensing the edge of the shutter disk at the second radial distanceoccurs when the shutter disk is misaligned on the shutter blade.
 23. Themethod of claim 17 further comprising: moving the shutter disk to thefirst position; transferring the shutter disk from a shutter blade tothe substrate support; moving the shutter blade at least partially intothe housing; and sensing the presence of the blade within the housingthrough a window disposed in the housing.
 24. A method for detecting theposition of a shutter disk within a physical vapor deposition chamberhaving a substrate support, comprising: moving the shutter disk awayfrom the substrate support; and changing a state of a first sensor inresponse to a position of an edge the shutter disk.
 25. The method ofclaim 24, wherein the step of changing the state of the first sensorfurther comprises: interrupting a beam emitted by the first sensor. 26.The method of claim 24 further comprising: changing a state of a secondsensor with an edge the shutter disk.
 27. The method of claim 26,wherein the step of changing the state of the second sensor furthercomprises: interrupting a beam emitted by the second sensor.
 28. Themethod of claim 26, wherein the step of changing the state of the secondsensor occurs when the shutter disk is misaligned to one side of ashutter blade supporting the shutter disk.